Payment Forensics in Banks: Common Breach Scenarios

Introduction: Why Payment Breaches in Banks Look Different Today 

Banking payment environments have undergone a fundamental shift. Transactions are now real time, architectures are API-driven, and payment workflows span core banking systems, fintech partners, cloud platforms, and national payment rails. This transformation has dramatically expanded the surface area where breaches can occur. 

Attackers today do not always break systems. They embed themselves within legitimate workflows, exploit trusted identities, and trigger transactions that appear operationally valid. As a result, the most damaging incidents in banks today are not always detected by traditional security controls. By the time an incident is recognised as a breach, funds may already have moved across multiple accounts, platforms, and jurisdictions. 

Role of Payment Forensics in Banks 

Payment forensics investigation in banking refers to the systematic investigation of payment-related incidents to understand how transactions were initiated, authorised, processed, and executed, and where controls failed along that journey. Unlike conventional security monitoring, payment forensics focuses on reconstructing how money moved, how workflows were manipulated, and how controls failed in sequence. It shifts the investigative lens from systems to transactions, from alerts to narratives, and from isolated events to interconnected failure chains. 

At its core, payment forensics in banks serves four critical objectives. First, it reconstructs breach timelines by correlating technical logs with financial events. Second, it traces transaction pathways across internal and external systems to identify points of manipulation. Third, it uncovers structural weaknesses in identities, workflows, and governance. Finally, it provides evidence that supports regulatory reporting, legal proceedings, and organisational learning. 

Common Payment Breach Scenarios in Banks 

Payment breaches in banks rarely follow a single, predictable pattern. They emerge at the intersection of technology, identity, and business workflows. Across SISA’s investigations in banking environments, certain patterns recur with striking consistency. These are not edge cases. They are structural weaknesses embedded in how modern payment systems are designed and governed. 

Scenario 1: Real-Time Payment Workflow Hijacking 

Real-time payment (RTP) environments such as UPI, IMPS, SWIFT, or RTP systems were built to eliminate friction. Attackers have learned to exploit that very design principle. Instead of breaking core systems, they hijack legitimate workflows. Transactions are executed using valid credentials, approved pathways, and legitimate interfaces. By the time alarms are raised, money has already moved beyond recovery. For example, in a recent security assessment of an internet banking environment, SISA discovered a critical flaw in the transaction authorization workflow which enabled the same OTP to be successfully reused to approve multiple fund transfers. This finding exposed a structural weakness: transaction controls were designed for sequential execution, while attackers operated in parallel. 

Scenario 2: Compromised Privileged Identities in Payment Systems 

Banks invest heavily in securing infrastructure, yet most high-impact breaches originate from something far less visible: privileged identities. Attackers obtain access to accounts with elevated permissions through phishing, credential theft, malware, or insider facilitation. They then reconfigure workflows, modify beneficiaries, and adjust thresholds – all through authorised actions, without any need for deploying malware. 

Scenario 3: Vendor and Third-Party Payment Ecosystem Breaches 

The modern bank is an ecosystem of fintech partners, payment service providers, cloud platforms, and vendors. Attackers understand this better than banks do. They target the weakest link in the ecosystem, manipulate external systems, and re-enter the bank through trusted integrations. Common techniques include altering vendor master records, redirecting payout accounts, or abusing partner APIs to trigger fraudulent transactions. 

Scenario 4: Insider-Assisted Payment Fraud 

Insider breaches are rarely about rogue employees. They are about how organisational trust is engineered into workflows. Approval hierarchies, exception handling, and override mechanisms are designed to keep business moving. Attackers exploit these design choices and selectively disable safeguards, often with minimal insider collaboration. 

Scenario 5: API Abuse in Open Banking and Integration Layers 

APIs were built to enable innovation and integration. In payment systems, they have quietly become channels for financial manipulation. Attackers do not exploit APIs as technical vulnerabilities, but as logical pathways by exploiting weak authentication, excessive permissions, or undocumented dependencies between APIs. By chaining API calls, they reconstruct payment workflows and trigger unauthorised transactions without breaching core systems. 

Scenario 6: Shadow IT and Shadow AI in Payment Operations 

Banks increasingly rely on automation scripts, low-code tools, and AI systems to accelerate payment operations. Many of these tools operate outside formal governance frameworks, creating blind spots that attackers exploit. When breaches occur, investigators face an uncomfortable reality: decisions were made by systems that cannot be explained, audited, or traced. Payment forensic investigation helps expose a new category of risk – not malicious code, but ungoverned intelligence. SISA’s findings from a web application penetration testing revealed flaws into an AIenabled workflow that accepted a crafted, conflicting prompt as a trusted execution command, that indicated a failure in multi-intent parsing and intent handling. This design flaw allowed the chatbot to execute a sensitive action, such as deleting purchase orders, without validation or authorization. 

Scenario 7: Multi-Stage Failure Chains in Payment Breaches 

The most consequential banking breaches are not single events. They are chains of small failures – each individually survivable, but collectively catastrophic, emerging from a sequence of small, overlooked weaknesses across identity, processes, technology, and governance. Banks do not suffer breaches because controls fail. They suffer breaches because failures are distributed. 

Conclusion 

Payment forensics is becoming a core capability for modern banks. It’s no longer just about investigating the occasional incident; it’s about building the resilience needed for a world of instant, API-driven, always-on payments. 

By understanding the common breach scenarios – from credential compromise to SWIFT/RTP manipulation and from insider abuse to API exploits, banks can prepare themselves better. And by strengthening forensic readiness, they can respond swiftly, recover effectively, and maintain the trust that the financial system depends on. The future of banking security will not be defined by how quickly breaches are detected, but by how deeply they are understood. The fundamental question for banks is no longer, “Are we secure?” It is: “Do we truly understand how our payment systems can fail?”